HomeMy WebLinkAboutItem 05.a❖ Crack Sealing
Cracks in asphalt left unattended
create problems. Simply, cracks
allow moisture to penetrate the
asphalt and enter the base
course and sub -grade and
weaken the road. The result,
over time, can range from a
surface failure Tike a pothole that
needs a quick fill to a larger area
that requires a patch. The Streets
Division has been aggressive in
expanding the crack - sealing
program over the last few years
based on pavement condition
rating. The objective is to crack seal
roadways early and reduce the
potential for failures from moisture.
Under the joint powers agreement
with several Dakota County
communities, a crack sealing
crew has been working in
Lakeville during the last couple of
weeks in June at various
locations throughout the City.
The process is to rout the crack to
provide a reservoir for the
sealant, blow out the crack to
ensure effective adhesion, and
then fill the crack with
rubberized asphalt. The main
purpose of crack sealing is to
prevent moisture from getting
LAKEVILLE OPERATIONS & MAINTENANCE
Christopher Petree, Director
June 201 1
into and underneath the road surface and limit deterioration of the asphalt
that leads to potholes and broader pavement failures.
❖ Manhole Repair
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Manholes structures, when constructed,
consist of a concrete tube incorporating
the sewer pipe and a cone section that
narrows to the manhole opening. In
many cases, the manhole cover and frame
are set on a ring at the top of the cone
section. Over time, the sealants used
deteriorate and let ground water infiltrate
the structure. Recent inspections of
structures by Utilities Division staff found
several structures where there was
evidence of infiltration around the
manhole frame. To solve the problem,
staff shoveled around the frame, lifted it off
the ring, and installed a product called
Ram -Nek to seal between the frame and
ring.
Dust Coating
Gravel road maintenance continues
to be an important part of the
Streets Division's operations. One
part of that maintenance is dust
control. Dust control is the spraying
of a stabilizer on the road surface to
limit the Toss of gravel. Cars trailing
dust on a gravel road means there is
a Toss of material important to
maintaining a stable road surface.
The fine particles, referred to as
fines, kicked up by vehicle tires are
important to keeping the larger
gravel locked in place on the
roadway. Without these fine
particles, the gravel has more
freedom of movement and over
time can be lost to the roads edge.
Repairing the road then requires
new gravel with a high
percentage of fines. To help
retain the fines and stabilize the
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roadway, the Streets Division applies magnesium chloride to the gravel roads.
Magnesium chloride is a hygroscopic chemical which means it draws moisture
from the air to keep the road surface damp and to help lock the fines and
gravel in place, reducing the loss of the fines as dust.
• Storm Sewer Liner
Recently, a small sinkhole appeared adjacent
to the storm sewer catch basin on Iron River
Trail at Iron River Court. The sinkhole was
not much larger than a pothole, but it did
indicate problems under the road surface
with the storm sewer pipe that connected
two catch basins. Video inspection of the
pipe showed holes resulting from rusted
concrete reinforcement bars that were
allowing sand to enter the pipe and be
washed downstream. Two solutions were
immediately available. One was to dig up
the roadway and replace the pipe. The
other was to use a cured in place pipe liner
to cover the sections with the holes. Using a
cured in place pipe liner was the more cost
effective and least disruptive
solution. The process involved
soaking a soft polyester liner with a
resin solution, sliding it over an air
bladder, and man handling both
the liner and air bladder into the
catch basin. Once in the catch
basin, it was pulled into position
and inflated, pushing the liner
against the sides of the pipe where
it was left to cure. Once cured, the
liner creates seamless and ^'
permanent pipe segment, covering -
any defects in the old pipe.
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Striping
Each year, in conjunction with other
Dakota County communities, the City
contracts for the repainting of the center
and fog Tines on City streets and the various
symbols such as stop bars, turn arrows, and
pedestrian crosswalks. The weather, as well
as the abrasive action of snowplows and
grit on the roadway, causes both the lane
markings and symbols to fade. Each spring,
the Streets Division evaluates and prioritizes
the lane markings and symbols in most
need of repainting. Those that do not need
painting are deferred to the next
year. The Streets Division
attempts to repaint all of the lane
markings and symbols over a
two -year cycle. Repainting and
maintaining Zane markings and
symbols is important to promote
traffic and pedestrian safety on
Lakeville's streets.
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